Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How To Interpret Graphs - Page 952 - AVS Forum | Home Theater Discussions And Reviews
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post #28531 of 28574 Old 01-11-2020, 10:43 PM
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Originally Posted by AustinJerry View Post
Just curious, why did you select measurement 11 when I recommended measurement 2?

If you have only one sub, I am not sure the purchase of a 2x4 just to be able to apply PEQ would be justified. But that is your decision.

The room mode calculator is only marginally useful with an irregular room shape.

To measure one main with sub, set the speaker to small, and select only the one HDMI output associated with the main speaker. For example, to measure center+sub, select HDMI3. Do NOT select HDMI4 as well. And to measure the main speaker without the sub, turn off the sub amp. It doesn't matter which speaker is selected as the timing reference--I use a side surround.

I am not sure there would be that much benefit to reading all of the back posts in this thread.
Hi, measurement 2 was done during my 1st exercise (try-out) where a few was taken along the mid side wall in an un-controlled environment (room ambient was not good enough), when I explained a bit on the differences between 2, 3 and 4. Sitting and sub distance were also not accurately recorded.

The next set of measurement 3-11 were done in a controlled environment, no one in the room, low noise (although still read 53-55 db on REW SPL), distance measured and recorded with sticker on the floor.

Thanks once again, sir.
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post #28532 of 28574 Old 01-13-2020, 02:04 PM
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Preferred by whom? Careful about conflating someone's subjective preference with objective superiority.
Good point. I should have been more careful about how Iwrote that. Here is what I thought of. I watched Toole
and what I understood from it is that 1st reflection was preferred my listeners.

I have been absorbing 1st/2nd reflection all along but now I want to try out to diffuse 1st reflection point for center channel as well as absorb as well to see how that sounds. I got into making the whole room Super black for better projector image quality and ended up wrapping almost everything b/w MLP and screen with black velvet. Black Velvet absorbs all the high frequencies. Very recently, I took it all off and will have only first 30" covered with Black Velvet which will also have 4" thick 703. Then I'm planning to do the checker pattern of 12"x12" 2D diffuser followed by 12"x12" 4" absorber at 1st reflection point of Center.

Anyway, thx for calling it out.
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post #28533 of 28574 Old 01-13-2020, 02:42 PM
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Originally Posted by harrisu View Post
I watched Toole and what I understood from it is that 1st reflection was preferred my listeners.
That doesn't mean listeners preferred using diffusion to scatter the 1st reflection in every direction. 500 pages into his book, Toole finally lays out a few suggested treatment schemes for the entire room. The only place he leaves completely blank (optional) is the side wall 1st reflection point. That's because the choice of absorption, diffusion or reflection comes down to personal preference. Hopefully you'll end up implementing your personal preference, not someone else's.
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post #28534 of 28574 Old 01-13-2020, 04:17 PM
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Absolutely. I'm not going to settle down until I am very satisfied with what I hear. I do know so far that I dont like too much absorption.

Sent from my SM-G950U1 using Tapatalk
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post #28535 of 28574 Old 01-14-2020, 08:39 AM
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Originally Posted by harrisu View Post
Absolutely. I'm not going to settle down until I am very satisfied with what I hear. I do know so far that I dont like too much absorption.

Sent from my SM-G950U1 using Tapatalk
You can do a combination of absorption and diffusion to help absorb low end while retaining or diffusing high end. I have GIK alpha panels at my first and 2nd reflection points on side walls and rear walls. Its basically a bass trap with diffusion that diffuses at 4000hz and up. Its all a matter or trying what you like.

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post #28536 of 28574 Old 01-14-2020, 12:22 PM
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You can do a combination of absorption and diffusion to help absorb low end while retaining or diffusing high end. I have GIK alpha panels at my first and 2nd reflection points on side walls and rear walls. Its basically a bass trap with diffusion that diffuses at 4000hz and up. Its all a matter or trying what you like.
Thx. I did the checker pattern with 12"x12" diffuser followed by 12"x12" absorbers at 1st reflection of Center and extending out to 3 feet vertically and horizontally. I"ll post the pics. The interesting part is that after I took out almost all the velvet and then installing the checkers and also covering first 30" around the screen, I see that RT graph changed a lot. I'll post before/after graph. Hopefully someone can explain what it means.

Subjectively, I can hear a lot of dynamics now. But I do feel like the dialog needs a bit more clean up. I'm planning to cover 1st reflection point on ceiling with an absorber and that should help.
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post #28537 of 28574 Old 01-14-2020, 12:30 PM
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That doesn't mean listeners preferred using diffusion to scatter the 1st reflection in every direction. 500 pages into his book, Toole finally lays out a few suggested treatment schemes for the entire room. The only place he leaves completely blank (optional) is the side wall 1st reflection point. That's because the choice of absorption, diffusion or reflection comes down to personal preference. Hopefully you'll end up implementing your personal preference, not someone else's.
Is there a general approach on where the diffusers should go on ceiling? I am using Aurolex Acoustics 2D diffusers and they are referred to as "gentle" diffusers. I'm planning to place some right above MLP with checker pattern of 1 diffuser and 1 absorber and then repeating the pattern. Bother diffuser/absorber are 12"x12" with 4" depth. Distance will be ~45" from year after they are placed.
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post #28538 of 28574 Old 01-14-2020, 01:11 PM
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Sooo... I used REW years ago on an old laptop with RCA out. No problem.


Trying again today on a new laptop with hdmi.


Following REW 101 PDF- I downloaded the ASIO, and adjusted the windows settings as noted.


Although I can test the hdmi output from windows settings for each channel fine- l, c, r, sub.... in REW I cant get hdmi to show up as an output choice in the drop down on the soundcard menu.



All I get is HD audio output 1 or 2 which when I run the pink noise generator just comes out the L or R speaker on my laptop.


I tried uninstalling and reinstalling... Ugh. Any ideas?
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post #28539 of 28574 Old 01-14-2020, 01:18 PM
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...and as I am sitting here googling for a fix- I am watching a youtube video on my laptop (mirrored on tv- so getting hdmi signal through receiver) and the audio is playing on all the speakers correctly.
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post #28540 of 28574 Old 01-14-2020, 01:58 PM
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Originally Posted by powerdubs View Post
...and as I am sitting here googling for a fix- I am watching a youtube video on my laptop (mirrored on tv- so getting hdmi signal through receiver) and the audio is playing on all the speakers correctly.
There is an ASIO troubleshooting section in the guide—did you follow those steps?
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post #28541 of 28574 Old 01-14-2020, 02:37 PM
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Yes- and it talks about getting the mic working, no specific reference to the hdmi option not showing.


I have found several threads of people with the same issue I have- and no answers. Some people 'have got it to work' after numerous software unistall / reinstall or reboots...no real answer. I have tried all that- over and over again...
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post #28542 of 28574 Old 01-14-2020, 02:39 PM
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Originally Posted by powerdubs View Post
Yes- and it talks about getting the mic working, no specific reference to the hdmi option not showing.


I have found several threads of people with the same issue I have- and no answers. Some people 'have got it to work' after numerous software unistall / reinstall or reboots...no real answer. I have tried all that- over and over again...
Yes, ASIO can be tricky to get working properly. There is an alternative called FlexASIO which you could try as well. I wish I could be of more help.
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post #28543 of 28574 Old 01-14-2020, 02:57 PM
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Yes, ASIO can be tricky to get working properly. There is an alternative called FlexASIO which you could try as well. I wish I could be of more help.
I tried downloading flexasio but oddly enough my computer won't let me run the exe- gives me an error / warning message and won't proceed.
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post #28544 of 28574 Old 01-14-2020, 03:10 PM
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I tried downloading flexasio but oddly enough my computer won't let me run the exe- gives me an error / warning message and won't proceed.
What kind of error? Post screenshot of the message?
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post #28545 of 28574 Old 01-14-2020, 03:17 PM
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Is there a general approach on where the diffusers should go on ceiling?
No, it depends on your preference and what you're trying to achieve. If you want a general sense of ambience, then you can randomly cover about 25% of the ceiling with diffusion and another 25% with absorption. That will keep the ceiling from being a giant reflector.

If you prefer a more targeted approach, think about what's going to be reflecting off the ceiling: all the base layer speakers. Then think about what you want to do with their reflections? Absorb? Diffuse? Reflect? My preference is to absorb ceiling reflections of the L/C/R speakers (I like a wide soundstage, but not necessarily a tall soundstage) and diffuse the ceiling reflections of the surround speakers (for a more ambient surround field, doesn't need to be as articulate as the front soundstage). YMMV.
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I'm planning to place some right above MLP with checker pattern of 1 diffuser and 1 absorber and then repeating the pattern.
Have someone hold a hand mirror right above the MLP. Look up. Do you see any speakers reflected in the mirror? If not, why are those treatments right above the MLP?
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post #28546 of 28574 Old 01-14-2020, 06:27 PM
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Thx. I did the checker pattern with 12"x12" diffuser followed by 12"x12" absorbers at 1st reflection of Center and extending out to 3 feet vertically and horizontally. I"ll post the pics. The interesting part is that after I took out almost all the velvet and then installing the checkers and also covering first 30" around the screen, I see that RT graph changed a lot. I'll post before/after graph. Hopefully someone can explain what it means.

Subjectively, I can hear a lot of dynamics now. But I do feel like the dialog needs a bit more clean up. I'm planning to cover 1st reflection point on ceiling with an absorber and that should help.
This will help you understand RT60 measurement. http://www.acousticfrontiers.com/und...-measurements/
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post #28547 of 28574 Old 01-14-2020, 08:07 PM
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If you prefer a more targeted approach, think about what's going to be reflecting off the ceiling: all the base layer speakers. Then think about what you want to do with their reflections? Absorb? Diffuse? Reflect? My preference is to absorb ceiling reflections of the L/C/R speakers (I like a wide soundstage, but not necessarily a tall soundstage) and diffuse the ceiling reflections of the surround speakers (for a more ambient surround field, doesn't need to be as articulate as the front soundstage). YMMV. Have someone hold a hand mirror right above the MLP. Look up. Do you see any speakers reflected in the mirror? If not, why are those treatments right above the MLP?
This makes a lot of sense. I agree. Instead of just putting the treatment right above MLP, should see where the first reflection is of surround speakers and treat them. Great point. Thx for that.

What about ceiling speakers? I assume that for that, we use side/back wall and find the first reflection point of them and treat them?

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This will help you understand RT60 measurement. http://www.acousticfrontiers.com/und...-measurements/
Thx for the link.
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post #28548 of 28574 Old 01-14-2020, 10:09 PM
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What about ceiling speakers? I assume that for that, we use side/back wall and find the first reflection point of them and treat them?
Sure. Even in this day and age of immersive audio, the front soundstage remains critical: that's where your attention is focused, whether watching a movie or listening to music.

With that in mind, I don't like surround info and height info reflecting off the front wall, for a couple of reasons: that's the wrong direction for those sounds to be coming from AND those reflections muddy the L/C/R info from the front soundstage. So the very first surface I would treat is the front wall, using broadband absorption. As an additional benefit, this also helps minimize cancellation notches resulting from nearby boundary reflections of the L/C/R speakers.

It's a different story for height info reflecting off the side/rear walls and surround info reflecting off the ceiling. Rather than absorb those reflections and end up with that sort of pin-point imaging and articulation that I like up front, I prefer to use diffusion for surround and height reflections that results in a more ambient and enveloping bubble. Only place that I ended up preferring absorption in the surround field was the middle third to half of the back wall (directly across from the centre speaker).

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post #28549 of 28574 Old 01-14-2020, 10:31 PM
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Only place that I ended up preferring absorption in the surround field was the middle third to half of the back wall (directly across from the centre speaker).
Agree 100% on the back wall absorption. But what about ceiling reflections from the front LCR speakers? I measured significant ceiling reflections in my setup.
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But what about ceiling reflections from the front LCR speakers?
Prefer to absorb those. But it's not a big deal to me if they're left untreated. Guess I'm easy to please. Reflections outside the front soundstage don't bother me much and, in some cases, I like them.
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post #28551 of 28574 Old 01-14-2020, 11:47 PM
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Do you think DSU surpasses the overall performance of DPLIIx when used in an Atmos configuration ? I still much prefer the overall results that DPLIIx provides, use it to listen to music.
It probably comes as no surprise that I do much prefer PLIIx for stereo music upmixing. Nothing to do with the height channels, but how it utilizes the surrounds.

Perhaps if there's anything further on this topic we should take it to the official-dolby-surround-upmixing-thread.

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post #28552 of 28574 Old 01-15-2020, 09:17 AM
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Sure. Even in this day and age of immersive audio, the front soundstage remains critical: that's where your attention is focused, whether watching a movie or listening to music.

With that in mind, I don't like surround info and height info reflecting off the front wall, for a couple of reasons: that's the wrong direction for those sounds to be coming from AND those reflections muddy the L/C/R info from the front soundstage. So the very first surface I would treat is the front wall, using broadband absorption. As an additional benefit, this also helps minimize cancellation notches resulting from nearby boundary reflections of the L/C/R speakers.

It's a different story for height info reflecting off the side/rear walls and surround info reflecting off the ceiling. Rather than absorb those reflections and end up with that sort of pin-point imaging and articulation that I like up front, I prefer to use diffusion for surround and height reflections that results in a more ambient and enveloping bubble. Only place that I ended up preferring absorption in the surround field was the middle third to half of the back wall (directly across from the centre speaker).
I do have the front stage covered with a single layer of LinAcoustic. Unfortunately, it covers half up from center. My speakers are BIG (JBL 4722N). With three of them and having 2 Mini Marty up front, I am left with no space. They cover up to 40" from Bottom up. So really no need to cover that part of wall. Therefore, I covered everything else above 40" for the front wall and also the side walls that are behind the AT screen.

I also agree with covering right behind MLP. I in fact also liked when I had the area covered a bit more towards left and right of that center point right behind MLP. In other words, right behind MLP plus half of Left/Righ seat area is covered on the back wall.

I haven't tried the ceiling diffusers yet. That'd be the last step.

Here is an interesting observation from last night listening to movie demos since they bring great sound dynamics: I had Center speaker 1st reflection on side walls diffused. Even though it was 12x12 diffuser followed by 12x12 absorber and then patter repeated in all directions, I realized that I didn't like Center channel diffused. So I removed the diffuser that was placed exactly where center channel has its 1st reflection and moved it more towards its 2nd reflection point, it sounded much better. Just a lot more cleaner in terms of dialog. So at this point, I have left Center 1st point to reflect (no absorbtion/diffusion) and liked it much better. Still loving the sound stage and how I can hear the high end effects very nicely with clarity of dialog.

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Agree 100% on the back wall absorption. But what about ceiling reflections from the front LCR speakers? I measured significant ceiling reflections in my setup.
Yep. Agreed
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Prefer to absorb those. But it's not a big deal to me if they're left untreated. Guess I'm easy to please. Reflections outside the front soundstage don't bother me much and, in some cases, I like them.
For LCR 1st reflection on ceiling, my plan is to absorb Center and leave L/R first and see how it sounds. I'm very sure that absorbing L/R will make music sound better. But I have to the path where I was absorbing a looot. Basically pretty much the whole ceiling/left/right walls were covered with Black Velvet from MLP to screen (~80%). That made the room much more dead. This time around, I'm going to do it slow and step by step to see how it sounds as I make the change and at any point, wouldn't want to loose the dynamics in high frequencies I hear now that I didn't before.
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post #28553 of 28574 Old 01-15-2020, 09:44 AM
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on ceiling, my plan is to absorb Center and leave L/R first and see how it sounds. I'm very sure that absorbing L/R will make music sound better. But I have to the path where I was absorbing a looot. Basically pretty much the whole ceiling/left/right walls were covered with Black Velvet from MLP to screen (~80%). That made the room much more dead. This time around, I'm going to do it slow and step by step to see how it sounds as I make the change and at any point, wouldn't want to loose the dynamics in high frequencies I hear now that I didn't before.
You must have better ears than I do. There is no way I can perceive the effectiveness of treatments with the granularity that you seem to exhibit. And it is not that easy to add, remove, and move around treatments for me, especially on the ceiling. On my side wall treatments, I chose GIK Acoustics 244 bass traps that have diffuser scatter-plates plates on the front, but I am not sure I can hear any difference. Regardless, I don't perceive that my room is over-treated, and am quite pleased with the sound stage.
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post #28554 of 28574 Old 01-15-2020, 09:50 AM
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I had Center speaker 1st reflection on side walls diffused. Even though it was 12x12 diffuser followed by 12x12 absorber and then patter repeated in all directions, I realized that I didn't like Center channel diffused. So I removed the diffuser that was placed exactly where center channel has its 1st reflection and moved it more towards its 2nd reflection point, it sounded much better. Just a lot more cleaner in terms of dialog. So at this point, I have left Center 1st point to reflect (no absorbtion/diffusion) and liked it much better. Still loving the sound stage and how I can hear the high end effects very nicely with clarity of dialog.
I went through a similar experience with all 3 front speakers. Tried absorption and diffusion at side wall 1st reflection points but kept coming back to bare side walls. Clearer dialogue, wider soundstage. A bit of absorption at the 2nd reflection points of the L/R speakers did sound nice. The only place I really like absorption on the side walls is at the contra-lateral (opposite side) 1st reflection points. I don't want sounds from the left side of the soundtage coming at me, however subtly, from the right side of the room. And vice versa. I really like ipsi-lateral (same side) 1st reflections, because they create a wide/lush soundstage, so those reflections are left untreated (gasp) for the L/R speakers.
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For LCR 1st reflection on ceiling, my plan is to absorb Center and leave L/R first and see how it sounds. I'm very sure that absorbing L/R will make music sound better.
Ceiling reflections should make the front soundstage appear taller. Anyway, good idea to experiment. IF you're doing a targeted approach to treatment, then always be asking yourself 2 things: why that particular location (on the wall or ceiling) and why that particular choice of treatment (absorption, diffusion, reflection).

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post #28555 of 28574 Old 01-15-2020, 02:17 PM
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Anyway, good idea to experiment. IF you're doing a targeted approach to treatment, then always be asking yourself 2 things: why that particular location (on the wall or ceiling) and why that particular choice of treatment (absorption, diffusion, reflection).
Yup. Good point Sanjay, and as you know my mantra is “What did you put where and why did you put it there?” Dead simple but a lot of moving parts!

Like peeling an onion as you realize that speakers have frequency dependent spatial patterns (dispersion), rooms have spatial dependent frequency response (modes), and all is inextricably commingled.
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post #28556 of 28574 Old 01-15-2020, 02:23 PM
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You must have better ears than I do. There is no way I can perceive the effectiveness of treatments with the granularity that you seem to exhibit. And it is not that easy to add, remove, and move around treatments for me, especially on the ceiling. On my side wall treatments, I chose GIK Acoustics 244 bass traps that have diffuser scatter-plates plates on the front, but I am not sure I can hear any difference. Regardless, I don't perceive that my room is over-treated, and am quite pleased with the sound stage.
I do have good hearing but there is more to it than that I believe. Is your room completely sealed and 100% dedicated to HT? If not then that might be playing a bigger role. For example, having a room with an open area might not show the results as aggressively as the one that is completely sealed. Also a room that is 100% dedicates to HT has everything done specifically for that purpose as compared to the room that is primarily used for any other reason.
Do you have a completely sealed dedicated HT room?
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post #28557 of 28574 Old 01-15-2020, 02:25 PM
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Originally Posted by sdurani View Post
I went through a similar experience with all 3 front speakers. Tried absorption and diffusion at side wall 1st reflection points but kept coming back to bare side walls. Clearer dialogue, wider soundstage. A bit of absorption at the 2nd reflection points of the L/R speakers did sound nice. The only place I really like absorption on the side walls is at the contra-lateral (opposite side) 1st reflection points. I don't want sounds from the left side of the soundtage coming at me, however subtly, from the right side of the room. And vice versa. I really like ipsi-lateral (same side) 1st reflections, because they create a wide/lush soundstage, so those reflections are left untreated (gasp) for the L/R speakers. Ceiling reflections should make the front soundstage appear taller. Anyway, good idea to experiment. IF you're doing a targeted approach to treatment, then always be asking yourself 2 things: why that particular location (on the wall or ceiling) and why that particular choice of treatment (absorption, diffusion, reflection).
Thx for all the feedback sdurani. Much appreciated. I'll try them out and will update as I go along
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post #28558 of 28574 Old 01-15-2020, 05:19 PM
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Hey REW crew, had a question about RTA measurements.

This arose out of idle curiosity about measuring certain "low volume" Disney/Marvel movies, I wanted to objectively measure the response of certain movie scenes to get a sense of avg vs. peak levels. I've never really used the RTA feature and figured that was the best method to analyze the levels of actual program content over a period of time.

So I placed my UMIK-1 mic in the MLP, set my master volume to -10, and played certain test scenes with explosions and loud noises, and started the RTA. My system is pretty accurately calibrated with MV 0.0 set to reference level. The graphs below are my peak vs. avg RTA results for two scenes: (1) Thanos destroying the Avengers facility in Endgame, and (2) the first few minutes of Chapter 3 of Mad Max: Fury Road.

Not knowing much about the RTA settings, I left everything pretty much at defaults in REW. For the "peak" measurements below, I left averages at "none". For the averages I set averages to "Forever" assuming that would continuously average from the point at which I clicked "Reset Averaging" to the point at which I stopped "recording" with the RTA. There is no smoothing applied.

I found the results a bit surprising. The peak levels in the 95-100dB range (around ~30Hz) correspond fairly well to the "max" levels when I use the SPL meter (C-weighting), although the SPL max is a few dB higher. Both graphs show a fairly consistent ~10dB gap between the "average" and "peak" levels.

But what surprised me was how little energy the RTA shows above the deep bass region. Taking the Endgame example, it's peaking at ~75dB at ~100Hz, down to ~65dB at ~200Hz... at 1kHz it's averaging ~35-40dB and peaking at 50-55dB, and lower and lower from there. I had relatively consistent results with several different movies and scenes so it's not just a fluke of a particular piece of content I used.

Surely this can't be right, right? Is there really such little energy up high? If dynamic content in the tweeter range (2kHz+) is below 50dB at -10 MV (which is pretty darn loud) then how does anyone ever blow a tweeter?

I feel like there's something I'm missing.

I can only assume that either (1) something is wrong with my technique (e.g. bad settings in REW) or (2) I am interpreting the results wrong or perhaps (3) I am not understanding what the RTA is supposed to be showing and I should be using a different tool. Or maybe, this is accurate?? I know people have done spectrum / amplitude analysis of movie soundtracks using other tools (like in the BEQ threads)... anyone who understands the REW RTA feature have any feedback?

RTA Measurements:

Avengers: Endgame (Thanos destroys the Avengers facility) at -10 volume:




Mad Max: Fury Road (first few minutes of Chapter 3) at -10 volume:

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post #28559 of 28574 Old 01-15-2020, 09:01 PM
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Hello: I'm new to using REW. Downloaded latest version, bought Umik-1 and mic stand. Added 90 degree calibration file, checked levels, turned off YPAO eq in the receiver, and started taking measurements of my subs. Here's where I am confused. I took five measurements that were exactly the same, yet REW gave me different results each time.....for the most part the graphs plotted with the same peaks and dips, but SPL results were all different despite no changes made to meetings or master volume. Is this expected or common? I thought I'd get five graph responses that looked identical. I also then turned on my 2nd sub and the new frequency response showed lower total SPL levels which I don't believe is possible because I can hear the higher SPL during the measurement where both subs are turned on. I greatly appreciate any help as right now I'm not confident the measurements are reporting out accurately.

Thanks,
Nathan
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post #28560 of 28574 Old 01-15-2020, 09:14 PM
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Quote:
Originally Posted by Nuggles View Post
Hello: I'm new to using REW. Downloaded latest version, bought Umik-1 and mic stand. Added 90 degree calibration file, checked levels, turned off YPAO eq in the receiver, and started taking measurements of my subs. Here's where I am confused. I took five measurements that were exactly the same, yet REW gave me different results each time.....for the most part the graphs plotted with the same peaks and dips, but SPL results were all different despite no changes made to meetings or master volume. Is this expected or common? I thought I'd get five graph responses that looked identical. I also then turned on my 2nd sub and the new frequency response showed lower total SPL levels which I don't believe is possible because I can hear the higher SPL during the measurement where both subs are turned on. I greatly appreciate any help as right now I'm not confident the measurements are reporting out accurately.

Thanks,
Nathan
In the years I have been using REW, I get consistent measurements without variations in SPL as you are reporting. I don’t think there is an issue with the software, so there must be something else going on. I don’t think you have provided enough information that would suggest a reason for the behavior you are observing. Perhaps try measuring something besides the subs to see if the behavior is similar.
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